There's a very good chance the Miami Marlins' two-game series against the Pittsburgh Pirates in Puerto Rico will not be held there because of concerns about the Zika virus, a person familiar with the situation said Tuesday.

The person spoke to The Associated Press on condition of anonymity because the teams said no decision had been made.

Marlins players attended a seminar on Zika that heightened concerns about playing the games in San Juan on May 30-31, team player representative Tom Koehler said. An announcement is expected by the end of the week regarding whether the games will be played as scheduled or moved, Koehler said.

U.S. Centers for Disease Control and Prevention gave a presentation on the disease to the Marlins and representatives of Major League Baseball and the players' union.

"The information was more shocking to both sides," Koehler said. "Maybe shocking isn't the correct word, but there was a lot more information and data and numbers thrown our way that we didn't have."

Marlins players voted on whether to play the games as scheduled, said Koehler. He declined to share the result but said there's a lot of concern within the clubhouse about playing in Puerto Rico.

If moved, the games would likely be played in Miami, because the Marlins are designated as the home team. Games against the Pirates are scheduled in Miami on June 1-2.

Discussions between MLB and the union are ongoing.

MLB officials, the Marlins and Pirates said last month they expected the games to be played as scheduled, but union head Tony Clark described the health and safety concerns as serious. U.S. health officials say Puerto Rico is the front lines of the nation's battle with Zika.

The CDC has said Zika can cause a birth defect called microcephaly, where infants are born with unusually small heads. The virus is most often spread by mosquito bites, but it also can be spread through sexual intercourse.

Pirates player rep Gerrit Cole said his understanding is MLB and MLBPA met Monday, and there was no consensus by the Pirates or Marlins players on whether to play or not. Cole said he anticipated an update later in the week.

MLB medical director Dr. Gary Green held an hour-long meeting with the Pirates on Saturday.

The Marlins were told a lot of precautions would be needed if they go to Puerto Rico, Koehler said. He said recommendations included staying in the team hotel as much as possible when not at the ballpark, and covering as much skin with clothing as possible.

"They told people if they had a pregnant spouse, that spouse should not go on the trip," Koehler said.

When asked if some players might skip the trip if the games are played as scheduled, Koehler said, "I don't know what the options are, because there has been no decision made."

Marlins and Pirates team officials said they had nothing new to say regarding a decision.